الفهرس 
Field proceduresOnly 14 pages are availabe for public view
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Abstract
This study was conducted at Sakha Agricultural Research Station to estimate the genetic variability in Giza-2 composite variety using four mating designs i.e. S I lines per se, S2 lines, design-I and design-I1 mating schemes. A total of 1 12 random plants were self-pollinated in 1994 to obtain S1 seeds. One plant from each S family was selfed to obtain 1 12 S2 families in 1995. At the same time 1 12 S ,’s (males) were crossed to four females per each in design-I mating scheme. Also, the 1 12 S I lines were divided into 14 groups, each with 8 Sl’s for starting design-11. For evaluation of yield trials, plants were grown to study the genetic parameters for nine traits in each mating design in 1996. The data recorded were silking date, plant height, ear height, ear length, ear diameter, No. of rows per ear, No. of kernels per row, No. of ear per 100 plants and grain yield (kg/plot). The obtained results concluded that: High significant differences among S I families per se were detected for all studied traits. The environmental variances were suitable, whereas the reliable estimates of coefficient of variability were obtained for the nine studied traits, the phenotypic variances were higher in magnitude than the total genetic variances for all studied traits. The total genetic variances showed significant differences in all studied traits. Heritability in broad sense revealed high estimate values for the nine studied traits as expected and ranged from 47 to 86%. Expected gain from selection was high for all traits. The correlation coefficient revealed significant and positive between grain yield and the other traits studied except sillting date which significant and negative toward earliness. The variation among S2 families exhibited highly significant differences for all traits with the exception of ear diameter which was significant only.